How Your Credit Score Is Actually Calculated
Five categories decide the number. They are not weighted the way most borrowers assume.
You have probably seen your credit score. You have probably never seen the arithmetic behind it, and that gap costs people money. You close an old card to tidy up your file and your score drops. You pay a balance to zero the day before applying for a loan and nothing moves. You check your own report and worry you have damaged something.
FICO produces the score most US lenders use. It runs from 300 to 850, and it is built from five categories of information. The weightings are published.
| Category | What it measures | Weight |
|---|---|---|
| Payment history | Whether you have paid on time | 35% |
| Amounts owed | How much of your available credit you are using | 30% |
| Length of credit history | How long your accounts have been open | 15% |
| New credit | Recent applications and newly opened accounts | 10% |
| Credit mix | The variety of account types you manage | 10% |
Two categories carry 65% of the score
Payment history and amounts owed together account for 65%. Everything else adjusts around the edges. If you want to move a score, work on those two and ignore the rest.
Payment history records whether you paid accounts as agreed. Pay a few days late and catch up before the next cycle, and your file will usually never show it, because lenders report delinquencies at 30 days. Once something lands as 30, 60 or 90 days late, it stays on the report for seven years from the date of the missed payment. Its weight fades as it ages, so a late payment from five years ago costs you far less than one from March.
Utilization is a snapshot, not an average
Amounts owed comes down to credit utilization, which is your balance on revolving accounts as a percentage of the limits on those accounts. The part that catches people is the timing. Your card issuer reports to the bureaus once a month, usually on the statement date rather than the due date. Whatever sat on the card at that moment becomes the number in your file.
Say you charge $3,000 a month on a $5,000 limit and clear it in full every cycle. You carry no debt and pay no interest. Your file may still show 60% utilization, because the snapshot happens before your payment lands. Pay down before the statement date instead of before the due date and the reported number changes.
Worth knowing
Utilization has no memory. Unlike payment history, the score recalculates it from whatever was last reported. A high balance reported in March stops mattering once a lower balance arrives in April. That makes utilization the fastest-moving input you control.
Closing an old card costs you twice
Length of credit history looks at the age of your oldest account, your newest, and the average of everything in between. Closing a long-held card does not erase its history immediately. A closed account in good standing can remain on your report for around ten years, and continues to count toward the age of your accounts while it is there. The history fades when the account finally drops off, which is a slow effect rather than a sudden one.
The immediate cost of closing is different, and larger. You lose that card's limit. Suppose you hold $20,000 in limits across four cards and carry $4,000 in balances. You sit at 20% utilization. Close a card with an $8,000 limit and the same $4,000 now measures against $12,000, which is 33%. Your borrowing did not change. Two categories moved against you anyway.
Checking your own report changes nothing
New credit covers applications. When a lender pulls your report to make a decision, that hard inquiry takes a few points and stops counting after twelve months, though it stays visible for two years.
Two things soften this. Checking your own report is a soft inquiry with no effect on the score at all, and the same goes for a card issuer pre-screening you for an offer. Scoring models also recognize rate shopping: several inquiries for the same kind of loan inside a short window count as one event. Comparing five mortgage lenders costs you what comparing one does. Opening five credit cards does not work that way.
Credit mix rarely justifies action
The last 10% looks at whether you handle different kinds of credit, revolving accounts like cards alongside installment accounts like a car loan. Someone holding only cards may score a little below an identical borrower who holds both.
Usually you should do nothing about this. Borrowing money you do not need, and paying interest on it, to improve a category worth a tenth of the score is a bad trade. Credit mix tends to fill itself in as you go through a normal financial life.
What a lender sees that a score app does not
Your score is a summary of the report, and lenders read both. Two applicants with identical scores can be treated differently because the underlying file differs.
A 700 built from six years of flawless payments on three accounts reads as stable. A 700 built from a recent bankruptcy followed by aggressive rebuilding reads as recovering. Both are 700. Lenders making manual decisions, particularly on mortgages, look at the shape of the history rather than the number alone.
Reason codes accompany a score whenever it is pulled. These are short statements identifying what held the score down most: high balances on revolving accounts, too many recent inquiries, insufficient credit history length. When a lender declines you or offers worse terms because of your report, federal law entitles you to an adverse action notice stating the principal reasons. That notice is more useful than the number, because it tells you which of the five categories is actually costing you.
What moves fastest, and what does not move at all
| Action | Typical effect | How quickly |
|---|---|---|
| Paying down revolving balances | Can be substantial | Next reporting cycle, often 30 days |
| Correcting a reporting error | Varies with the error | Once the dispute resolves, 30-45 days |
| Becoming an authorized user | Modest to substantial on a thin file | One to two cycles |
| A new on-time payment | Small, cumulative | Monthly, compounding over years |
| An inquiry aging past 12 months | Small | Automatic |
| A late payment aging | Weight fades gradually | Years |
| Paying a collection | Depends on the scoring model | Varies; the account may remain either way |
That last row deserves a note. Newer scoring models ignore paid collections. Older models do not distinguish as sharply. Paying a collection is often the right thing to do for reasons unrelated to your score, but expecting a jump is a reasonable way to be disappointed.
Which model a mortgage lender runs is currently in transition. Classic FICO was the single required model for loans sold to Fannie Mae and Freddie Mac for years, and it remains widely used. VantageScore 4.0 is available through a limited rollout to approved Fannie Mae and Freddie Mac lenders. FICO 10T has been approved but is not yet generally eligible for loan delivery to those enterprises, though the historical score data supporting it was published in July 2026. FHA and VA run their own timelines, which are not at the same stage.
The practical consequence for a borrower is unchanged: the number in a free monitoring app is usually not the number a mortgage lender pulls, and the only way to know which model applies to your application is to ask the lender.
The rules underneath all of this
Credit reporting in the United States runs on the Fair Credit Reporting Act, which sets what can be collected, how long it stays, who may access it and what happens when you dispute something. Two rights are worth knowing specifically.
Adverse action notices. If information in your report causes a lender to decline you or charge you more, you must be told, and told which report was used. You can then request that report free of charge.
Free reports. You are entitled to your report from each of the three nationwide bureaus through the official federally authorized service. Reading the data is more useful than watching the number.
The Consumer Financial Protection Bureau publishes both the underlying rules and plain-language explanations of these rights.
You do not have one score
FICO maintains multiple versions of its model, and lenders in different industries use different ones. Mortgage lenders often run older versions than the free app on your phone shows you. VantageScore, built by the three credit bureaus, uses the same 300 to 850 range and weights the inputs its own way.
Equifax, Experian and TransUnion also hold different data, because not every lender reports to all three. A twenty or thirty point spread between bureaus is ordinary and does not mean one of them made a mistake.
Federal law entitles you to your reports from each bureau through the official annual credit report service. The reports show the underlying data rather than a score, which makes them the more useful thing to read. An account you do not recognize, a wrong balance, a late payment that never happened: each one is worth disputing, and each one feeds the categories above.
This article is general information about how consumer finance products work in the United States. It is not financial, tax or legal advice and is not a recommendation of any specific product or provider. Rules and pricing vary by state and by institution.